Booster system.



Patented, Dec. 9, I902.

G. BAEHR.

BOOSTER SYSTEM.

(Application filed Feb 14, 1902.1

(No Model.)

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PATENT OFFICE.

GEORGE BAEHR, OF MOKEESPORT, PENNSYLVANIA, ASSIGNOR TO NATIONAL TUBECOMPANY, OF PITTSBURG, PENNSYLVANIA, A CORPORATION OF NE W JERSEY.

BOOSTER SYSTEM.

SPECIFICATION forming part of Letters Patent No. 715.236, dated December9, 1902.

Application filed February 14, 1902- Serial No. 94,122. (No model.)

To all whom, it may concern:

Be it known that I, GEORGE BAEHR, a resident of McKeesport, in thecounty of Allegheny and State of Pennsylvania, have invented a new anduseful Improvement in Booster Systems; and I do hereby declare thefollowing to be a full, clear, and exact description thereof.

My invention relates to electrical generat- 1o ing and translatingsystems; and its object is to provide a system of this kind whereby thevoltage and amperage of the current generated and used is automaticallyregulated to correspond to the load thrown upon the mo- [5 tor or othertranslating device.

More specifically stated, the object of my invention is to provide asystem of this character which is adapted to drive a motor at a givenspeed when running idle or under a friction or light load and at greaterspeed when running under a heavier load, the current for producing thiseffect being automatically controlled.

In many industrial plants the machines are used intermittently, and thenature of the work is such that when the load is put on the machine, or,in other words, when the material to be operated upon is presented tothe machine, the latter should not exceed a cer- 3o tain speed;otherwise it is difficult to handle the work, and there is alsoliability of damaging the same. It frequently occurs, however, thatafter the work has been begun the machine can be considerably speeded upwithout 'detrimentally affecting the work, and sometimes with the effectof improving it. If a constant-speed or constant-current motor beemployed for driving such machines, the quantity of current consumedwill of course 40 be automatically regulated by the load on the machine,and the counter electromotive force generated when the machine isrunning idle will keep the speed of the motor substantially uniform; butwhen the load is thrown on the machine the speed of the motor willslightly decrease, although, theoretically, it is presumed to remainconstant. By the.use of such motors and an ordinary generating systemthe motor will not be speeded up after the load has been thrown on themachine unless some manual means be employed-such,

for instance, as cutting out a resistance or weakening the field of themotor. The former, however, is wasteful of current, and the latterdecreases the torque of the motor.

The object of my invention is to provide an electrical system whereby amachine of the character described will when idle or under a frictionload run at a comparatively slow speed and without wastage of current,but whereby when the load is thrown on said machine the current will beautomatically increased both in voltage and amperage, so that themachine is speeded up.

My invention further consists in certain details of arrangement of thesystem, as will hereinafter appear.

The accompanying drawingshows diagrammatically one arrangement of mybooster system.

In the drawing the main generator is shown at 15, and this may be of anyof the well-known types, preferably a constant-current generator. To theterminals of this generator are connected the power-mains l6 and 17. Thetranslating device of the system may be represented by a motor whosearmature is shown at 18, and this will be connected by suitable gearingto the machine or machines to be driven. The field of this motor ispreferably compound wound, although this is not absolutely essential, asa shunt wound motor would answer for some purposes. The shuntwindingisshown at 19 and is connected across the power-mains, as shown. Theseries wind ing of the field is shown at 20 and has one terminalconnected to one of the armaturebrushes, while the other terminal isconnected to the motor-generator or booster, as will be hereinafterdescribed. The motor is connected to the power-mains by any suitableswitch or starting device, one suitable for this purpose being shown at21, the same comprising a switch arm or blade 22, connected to thepower-main 17 and adapted to pass onto a contact-strip 23, connected tothe shunt-field 19, and also pass over contact-pieces 24,which areseparated by a resistance agency, such as coils of fine wire 25, andconnected to the armature 18 of the motor. The strip 23, is of suchlength that when the switch-arm 22 is moved to close the circuit thefield 19 will be first energized and brought to its full strength beforethe circuit through the armature is closed, and as the switch-arm 22 ismoved along the resistance is gradually cut out, thus graduallyincreasing the current through the armature and avoiding injury to thesame.

The booster or motor-generator is shown at 27, and this may be of anyapproved type of motor-generator, preferably having the motor andgenerator directly coupled, as 'by means of the shaft 28. Themotor-armature is shown at 29 and the motor-field at 30. This motor isconnected across the powermains, as shown, and in the circuit is placeda suitable switch or starting device 31, which may be of any approvedform and is shown of the same construction as the starting device 21 inthe primary-motor circuit.

The generator-armature of the booster is shown at 32, and the field'ispreferably of a different type, composed of two windings 33 and 34. Theformer is of large wire and large current-carrying capacity and is inseries with the generator-armature 32 and with the series winding 20 andarmature 18 of the primary motor. The other field-winding 34 is of smallwire and correspondingly small current-carrying capacity and wound in adirection opposite to the winding of the field 33,

and it is connected across the power-mains, as shown. Suitable meanswill be provided for regulating the strength of each of these fields,and this is most conveniently accomplished by putting in thefield-circuits variable resistance devices, (shown diagrammatically at36 and 37.) The variable-resistance device 36 in the circuit of theshunt or differential field 34 is in series therewith, while thevariable resistance 37in the circuit of the series field 33 is inparallel therewith, although these arrangements may be varied, ifdesired or necessary. A variable-resistance device is also preferablyput in the circuit of the shunt-winding 19 of the primary motor, asshown at 38, so that the strength of the field of said motor can bevaried. Should it be desired to increase the speed of the motor abovethat given by the booster, this resistance device is adjusted to weakenthe field 19, thus giving the increased speed to the armature 18.

The operation of this system is as follows: We will assume that the maingenerator 15 is operating in the usual manner and that the circuitsthrough both the primary motor or other translating device and thebooster 27 have been closed by suitably moving the switches 21 and 31.Current from the powermain 16 will then flow through both the shunt andseries windings 19 and 20 of the primary motor and cause rotation of thearmature 18 thereof in the well-understood manner. The

cuits.

the motor of the booster, thereby rotating said motor and the armature32 of the generator. Current will also be flowing through theshunt-Winding 34 of this generator; but the variable resistances 36 and37 will have been so adjusted that when the motor 18 is running idle orunder a friction load or, more strictly speaking, at its desired lowerspeed, the ampere turns of the two fieldwindings 33 and 34 will be thesame, and as they work in opposition they will neutralize each other. Asa consequence, no magnetism will manifest itself at the ends of thepolepieces, and no current will be generated by the armature 32;bntsaidarmature will merely rotate idly and will not interfere with the flow ofthe current through the same to the series field 20 of the primarymotor. As soon as the load or the additional load, as the case may be,is thrown on the primary motor it will tend to decrease the torque ofthe armature 18, thereby decreasing the counter electromotive force andpermitting more current to flow through said armature, which currentmust necessarily come by way of the series field 33 of themotor-generator, so that said field 33 is increased in strength, whilethe oppositely-wound field 34 remains of the same strength. As aconsequence the field becomes overbalanced, or, more strictly speaking,a magnetic field is established, so that the rotation of the armature 32in this field will generate additional current, and this current, withthe connections shown, must flow through the series field 20 andarmature 18 of the primary motor, thus increasing both the voltage andthe amperage flowing through said field and armature and correspondinglyincreasing the torque and speed of said motor. As long as this load oradditional load remains on the motor 18 the extra current will begenerated by the booster and transmitted to strengthen the field andarmature of the primary motor, thereby maintaining the higher speed ofthis motor during the continuance of the load. As soon, however, as theload is taken off this motor the current flowing through the motorfurnishes an excess of torque, which momentarily causes the speed toincrease, thus increasing the counter electromotivo force and decreasingthe current flowing through the armature 18 and the series field 33 ofthe booster. As a consequence, the fields of this motor-generator willagain neutralize each other and stop the generation of current thereby,and the primary motor will drop back to its normal or slow speed. Theshunt-winding 19 of the primary motor prevents the armature 18 fromracing when the load is taken ofi, as would be the case if only theseries winding 20 were used. This is well understood by those skilled inthe art and need not be further described.

It will be observed that by the use of my system the primary motor willrun at one speed when under a friction or light load and at an increasedspeed when under a heavier load and that this regulation takes placeantomatically and without any manual manipulation. It will beunderstood, of course, that all the details of arrangement shown are notnecessary; but these may be varied within limits Without distu rbing theeffect produced. For instance, a single source of current, such as thegenerator 15, need not be employed, as separate sources of current mightbe used for the primary motor and for the boostermotor, if desired.Furthermore, this booster need not be of the motor-generator type, asshown, as an engine-driven generator whose fields are excited from anoutside source of current would give the same elfect. So, too, theseries winding 20 of the primary motor is not absolutely essential, as ashunt-wound motor can be used. In that case the series field of thebooster will be connected directly to the armature 18 of the primarymotor. For convenience and efficiency, however, the arrangement shown inthe drawingis preferred. The main generator 15 will of course be locatedat any desired point, and the booster 27 will preferably be located inproximity to the translating circuit or device, and when the translatingdevice is a motor, as shown, the booster will be in proximity to themachine driven by the primary motor or just outside of the shop or millin which the latter is located. The primary motor will of course belocated as close as convenient to the machine to be driven.

What I claim as my invention, and desire to secure by Letters Patent, is

1. In an electric-booster system, the combination with a motor, of asource of current therefor, and automatic means for increasing theamperage and voltage of the current at the motor-terminals in proportionto the increase of the load on the motor.

2. In an electric-booster system, the combination with a motor, of asource of current therefor, and means controlled by an increase of theload on the motor for increasing in like proportion the amperage andvoltage of the current at the terminals of the motor.

3. In an electric-booster system, the combi nation with a motor, of asource of current therefor, and a booster, the field of which isestablished by current flowing to the motor in excess of a predeterminedamount.

4. In an electric-booster system, the combination with a motor having ashunt-winding, of a generator supplying current for said motor, and asource of current for exciting the field of said generator, said fieldbeing in series with the armature of the motor whereby an increase inthe load on the motor will cause a proportionate increase in strength ofthe generator-field.

5. In an electric-booster system, the combination with a motor having ashunt-winding, of a generator having a differentially-wound field, and asource of current for exciting said generator-fields, one of saidgeneratorfields being in series with the armature of the motor wherebyan increase in the load on the motor will cause a proportionate increasein strength of the generator-field.

6. In an electric-boostersystem, the combination with a motor, of agenerator supplying current therefor, said generator having adifferentially-wound field, one of said windings beingin series with themotor-armature and said fields being so proportioned as to neutralizeeach other when the motor is running under a friction or light load, anda source of current for exciting said generatorfields.

7. In an electric-booster system, the combination with a motor, of agenerator having two field-windings of different carrying capacities andwound in opposite directions, the larger of said field-windings being inseries with the armature of the motor and said windings being soproportioned as to neutralize each other when the motor is running undera friction or light load, and a source of current for exciting saidgenerator-fields.

8. In an electric-booster system, the combination with a motor having ashunt-winding, of a generator having two field-windings oppositelywound, one of said windings being in series with the armature of themotor and said windings being so proportioned as to neutralize eachother when the motor is running under a friction or light load, and asource of current for exciting said generatorfields.

9. In an electric-booster system, the combination with a motor, of agenerator having two field-windings of different carrying capacities andoppositely wound, the smaller of said windings being in shunt with thegenerator-armature and the other of said windings being in series withthe generator-armature and with the motor-armature, said windings beingso proportioned as to neutralize each other when the motor is runningunder a friction or light load, and a source of current for excitingsaid generator-fields.

10. In an electric-booster system, the combination with power-mains, ofa motor having a shunt-winding connected across said mains, and abooster having a differentiallywound field, one of said windings beingconnected across said mains and the other being in series with thegenerator-armature and with the motor-armature, said windings being soproportioned as to neutralize each other when the motor is running undera friction or light load.

11. In an electric-booster system, the combination with power-mains, ofa motor having a shunt-winding connected across said mains, and amotor-generator having its motor connected across said mains and itsgenerator having two field-windings of difierent carrying capacities andwound in opposite directions, the smaller of said windings beingconnected across said mains and the larger of said windings being inseries with the generator-armature and with the motor-armature,

said windings being so proportioned as to neutralize each other when themotor is running under a friction or light load.

12. In an electric-booster system, the combination with a compound-woundmotor, of a source of current-for the shunt-windingthereof, a generatorhaving a series field and its armature in series with the series windingand armature of the motor, and a source of current for the field of saidgenerator.

13. In an electric-booster system, the com bination with acompound-wound motor, of a source of current for the shunt-windingthereof, a generator having a difierentially-wound field, one of saidwindings being in series with the series winding and armature of themotor, and a source of current for exciting said generator-field.

14. In an electric-booster system, the combination with a compound-woundmotor, of a source of current for the shunt-windingthereof, a generatorhaving two field-windings of different carrying capacities and wound inopposite directions, the larger of said fieldwindings being in serieswith the series winding and armature of the motor, and a source ofcurrent for exciting said generator-fields.

15. In an electric-booster system, the combination with a compound-woundmotor, of a source of current for the shunt-winding of said motor, avariable resistance in the circuit of said shunt-winding, a generatorhaving two field-windings oppositely wound, one of said windings beingin series with the series winding and armature of the motor, and asource of current for exciting said generator-fields.

16. In an electric-booster system, the combination with a compound-woundmotor, of a source of current for the shunt-winding of said motor,agenerator having two field-windings oppositely wound, one of saidwindings being in shunt with the generator-armature, and the other beingin series with the generator-armature and with the series winding andarmature of the motor, variable resistances in circuit with thegenerator-field windings, and a source of current for exciting saidgenerator-fields.

17. In an electric-booster system, the combination with power-mains, ofa compoundwound motor, the shunt-winding of which is connected acrosssaid mains, and a booster having a differentially-wound field, one ofsaid windings being connected across said mains and the other being inseries with the generator-armature and with the armature and serieswinding of the motor.

18. In an electric-booster system, the combination with power-mains, ofa compoundwoun'd motor, the shunt-winding of which is connected acrosssaid mains, and a booster having two field-windings of differentcarrying capacities and wound in opposite directions, the smaller ofsaid windings being connected across said mains and the larger of saidwindings being connected in series with the generator-armature and withthe armature and series winding of the motor.

19. In an electric-booster system, the combination with power-mains, ofa compoundwound motor, the shunt-winding of which is connected acrosssaid mains, and a motorgenerator having its motor connected across saidmains and its generator having two fieldwindings oppositely wound, oneof said windings being in shunt with the generator-armature andconnected across said mains and the other being in series with thegenerator-armature and with the series winding and armature of themotor.

20. In an electric-booster system, the combination with power-mains, ofa compoundwound motor, the shunt-winding of which is connected acrosssaid mains, and a motorgenerator having its motor connected across saidmains, and its generator having two fieldwindings of different carryingcapacities and wound in opposite directions, the smaller of saidwindings being connected across said mains and in shunt with thegenerator-armature and the larger of said windings being in series withthe generator-armature and with the series winding and armature of themotor.

In testimony whereof I, the said GEORGE BAEHR, have hereunto set myhand.

GEORGE BAEHR.

Witnesses:

F. W. WINTER, ROBERT C. TOTTEN.

